1. Field of the Invention
This invention relates to vacuum-sealed packaging of objects in flexible bags and in particular to packaging for use with objects, such as meat products, having sharp projections.
2. Description of the Prior Art
It is conventional in packaging meat products and the like to place the meat product in a bag formed of a suitable heat sealable material and causing the bag to be drawn about the meat product under vacuum so as to vacuum seal the meat product in the bag thereby to effectively package the meat product for long shelf life.
It has been found, however, that at times relatively sharp projections, such as bone projections of the meat products, may puncture the bag material, thereby causing loss of vacuum and resultingly undesirable degradation of the packaged meat product.
One attempted solution to this problem has been the provision of a bone guard conventionally comprising a sheet of suitable waxed cloth or other tear-resistant material which is placed by hand in overlying relationship to the meat product sharp projections. The sheet must be maintained in the desired position relative to the meat product while the meat product is inserted into the flexible bag.
This method of preventing perforation of the pouch has the serious disadvantage of relatively high cost and low product rate. Further, at times, the bone guard slips from the desired position during the insertion of the meat into the bag, thereby rendering the bag effectively unprotected.
The background art includes a number of pertinent U.S. Letters Patent. Illustratively, U.S. Letters Patent 2,891,870 of Meyer S. Selby et al, shows a method of packaging utilizing the conventional internal bone guard member presenting the problem discussed above.
Carl A. Stickel shows, in U.S. Pat. No. 3,264,165, an insulating bag formed of a large number of different layers including vinyl chloride, polyurethane and polyethylene materials. Stickel teaches the use of foam for protecting the resin films from being punctured.
Frederick B. Schelhorn shows, in U.S. Pat. No. 3,342,613, a laminated blanket including a moisture-absorbent layer and a polyethylene or polyvinyl chloride layer.
O. R. Titchenal shows an abuse resistant bag in U.S. Pat. No. 3,494,457 wherein an outer envelope is fitted loosely over an inner envelope to protect the inner envelope from punishment.
In U.S. Pat. No. 3,559,800, John Parkman Butler et al show a multiply pouch formed of heat sealable materials. Butler et al teach the formation of pouches of polyethylene, polypropylene and vinyl chloride.
O. R. Titchenal et al show, in U.S. Pat. No. 3,625,348, a packaged article wherein the outer covering comprises a multilayer flexible plastic sheet including a self-adhering plastic inner layer facing the packaged article. Titchenal et al disclose a wide range of materials for use in the different layer.
Ezekiel J. Jacob, in U.S. Pat. No. 3,669,256, shows a surgical blade package wherein a multilayer bag is formed of a wide range of materials.
Harri J. Brax et al show a multiply laminate for use as a packaging film in U.S. Pat. No. 3,741,253 wherein the different layers are formed of different disclosed materials. This patent is concerned with the problem of packaging bone-in cuts of meat and relies on the use of a specific inside coating of the plastic film to provide a good barrier layer.
Fred B. Shaw et al, in U.S. Pat. No. 3,932,693, show a laminated packaging film formed of a number of different synthetic resins.
Josef Vercauteren shows a packaging film formed of a number of different synthetic resins in U.S. Pat. No. 3,949,135 and teaches that the bag be abrasion, puncture and tear resistant. Vercauteren discloses a wide range of materials from which his film may be formed.